MySQL Cluster 7.5.9 has been released

Dear MySQL Users,

MySQL Cluster is the distributed, shared-nothing variant of MySQL.
This storage engine provides:

   - In-Memory storage - Real-time performance (with optional
     checkpointing to disk)
   - Transparent Auto-Sharding - Read & write scalability
   - Active-Active/Multi-Master geographic replication

   - 99.999% High Availability with no single point of failure
     and on-line maintenance
   - NoSQL and SQL APIs (including C++, Java, http, Memcached
     and JavaScript/Node.js)

MySQL Cluster 7.5.9, has been released and can be downloaded from

   http://www.mysql.com/downloads/cluster/

where you will also find Quick Start guides to help you get your
first MySQL Cluster database up and running.

MySQL Cluster 7.5 is also available from our repository for Linux
platforms, go here for details:

   http://dev.mysql.com/downloads/repo/

The release notes are available from

   http://dev.mysql.com/doc/relnotes/mysql-cluster/7.5/en/index.html

MySQL Cluster enables users to meet the database challenges of next
generation web, cloud, and communications services with uncompromising
scalability, uptime and agility.

More details can be found at

   http://www.mysql.com/products/cluster/

Enjoy !

Changes in MySQL NDB Cluster 7.5.9 (5.7.21-ndb-7.5.9) (2018-01-17, 
General Availability)

    MySQL NDB Cluster 7.5.9 is a new release of MySQL NDB Cluster
    7.5, based on MySQL Server 5.7 and including features in
    version 7.5 of the NDB
    (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster.html)
    storage engine, as well as fixing recently discovered bugs in
    previous NDB Cluster releases.

    Obtaining MySQL NDB Cluster 7.5.  MySQL NDB Cluster 7.5
    source code and binaries can be obtained from
    http://dev.mysql.com/downloads/cluster/.

    For an overview of changes made in MySQL NDB Cluster 7.5, see
    What is New in NDB Cluster 7.5
(http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-what-is-new-7-5.html).

    This release also incorporates all bug fixes and changes made
    in previous NDB Cluster releases, as well as all bug fixes
    and feature changes which were added in mainline MySQL 5.7
    through MySQL 5.7.21 (see Changes in MySQL 5.7.21 (Not yet
    released, General Availability)
(http://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-21.html)).

    Bugs Fixed

      * NDB Replication: On an SQL node not being used for a
        replication channel with sql_log_bin=0
(http://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_sql_log_bin)
        it was possible after
        creating and populating an NDB table for a table map
        event to be written to the binary log for the created
        table with no corresponding row events. This led to
        problems when this log was later used by a slave cluster
        replicating from the mysqld where this table was created.
        Fixed this by adding support for maintaining a cumulative
        any_value bitmap for global checkpoint event operations
        that represents bits set consistently for all rows of a
        specific table in a given epoch, and by adding a check to
        determine whether all operations (rows) for a specific
        table are all marked as NOLOGGING, to prevent the
        addition of this table to the Table_map held by the
        binlog injector.
        As part of this fix, the NDB API adds a new
        getNextEventOpInEpoch3()
(http://dev.mysql.com/doc/ndbapi/en/ndb-ndb-getnexteventopinepoch3.html)
        method which provides information about
        any AnyValue received by making it possible to retrieve
        the cumulative any_value bitmap. (Bug #26333981)

      * A query against the INFORMATION_SCHEMA.FILES
        (http://dev.mysql.com/doc/refman/5.7/en/files-table.html)
        table returned no results when it included an ORDER BY
        clause. (Bug #26877788)

      * During a restart, DBLQH loads redo log part metadata for
        each redo log part it manages, from one or more redo log
        files. Since each file has a limited capacity for
        metadata, the number of files which must be consulted
        depends on the size of the redo log part. These files are
        opened, read, and closed sequentially, but the closing of
        one file occurs concurrently with the opening of the
        next.
        In cases where closing of the file was slow, it was
        possible for more than 4 files per redo log part to be
        open concurrently; since these files were opened using
        the OM_WRITE_BUFFER option, more than 4 chunks of write
        buffer were allocated per part in such cases. The write
        buffer pool is not unlimited; if all redo log parts were
        in a similar state, the pool was exhausted, causing the
        data node to shut down.
        This issue is resolved by avoiding the use of
        OM_WRITE_BUFFER during metadata reload, so that any
        transient opening of more than 4 redo log files per log
        file part no longer leads to failure of the data node.
        (Bug #25965370)

      * In certain circumstances where multiple Ndb objects were
        being used in parallel from an API node, the block number
        extracted from a block reference in DBLQH was the same as
        that of a SUMA block even though the request was coming
        from an API node. Due to this ambiguity, DBLQH mistook
        the request from the API node for a request from a SUMA
        block and failed. This is fixed by checking node IDs
        before checking block numbers. (Bug #88441, Bug
        #27130570)

      * When the duplicate weedout algorithm was used for
        evaluating a semi-join, the result had missing rows. (Bug
        #88117, Bug #26984919)
        References: See also: Bug #87992, Bug #26926666.

      * A table used in a loose scan could be used as a child in
        a pushed join query, leading to possibly incorrect
        results. (Bug #87992, Bug #26926666)

      * When representing a materialized semi-join in the query
        plan, the MySQL Optimizer inserted extra QEP_TAB and
        JOIN_TAB objects to represent access to the materialized
        subquery result. The join pushdown analyzer did not
        properly set up its internal data structures for these,
        leaving them uninitialized instead. This meant that later
        usage of any item objects referencing the materialized
        semi-join accessed an initialized tableno column when
        accessing a 64-bit tableno bitmask, possibly referring to
        a point beyond its end, leading to an unplanned shutdown
        of the SQL node. (Bug #87971, Bug #26919289)

      * When a data node was configured for locking threads to
        CPUs, it failed during startup with Failed to lock tid.
        This was is a side effect of a fix for a previous issue,
        which disabled CPU locking based on the version of the
        available glibc. The specific glibc issue being guarded
        against is encountered only in response to an internal
        NDB API call (Ndb_UnlockCPU()) not used by data nodes
        (and which can be accessed only through internal API
        calls). The current fix enables CPU locking for data
        nodes and disables it only for the relevant API calls
        when an affected glibc version is used. (Bug #87683, Bug
        #26758939)
        References: This issue is a regression of: Bug #86892,
        Bug #26378589.

      * The NDBFS block's OM_SYNC flag is intended to make sure
        that all FSWRITEREQ signals used for a given file are
        synchronized, but was ignored by platforms that do not
        support O_SYNC, meaning that this feature did not behave
        properly on those platforms. Now the synchronization flag
        is used on those platforms that do not support O_SYNC.
        (Bug #76975, Bug #21049554)


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